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Frog waste meal and frog meal

Datasheet

Description
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Common names 

Frog waste meal, frog waste, frog meal

Species 
Related feed(s) 
Description 

Frogs make a substantial contribution to the gastronomy of several cultures where frog legs are eaten as a delicacy. The frog legs processing industry yields about 45-65% of waste including the heads, viscera, skins and upper parts of the body. This by-product can cause considerable environmental problems when discarded into the environment and its utilization as a feed ingredient has been investigated since the 1970s, particularly in India, Indonesia and Turkey (Tokur et al., 2008). Numerous true frog species from the Ranidae family are harvested or farmed for food, including the European edible frog (Pelophylax kl. esculentus complex), the American bullfrog (Lithobates catesbeianus), the Chinese edible frog (Hoplobatrachus rugulosus) and, in Indonesia, the crab-eating frog (Fejervarya cancrivora) and Giant Javan Frog (Limnonectes macrodon) (Gratwicke et al., 2010). Dried and milled whole frogs (frog meal) have been studied in Nigeria as a feed for catfish species (Fagbenro et al., 1993; Achionye-Nzeh et al., 2003). Frog waste and frog meal are protein sources that can be used to replace fish meal in poultry and fish diets.

Distribution 

Frog legs are eaten all around the world, notably in Europe, North America and Asia. Since the 1950s, the frog legs market has shifted from seasonal harvest for local consumption to year-round global trade. Overexploitation in Europe and North America led to loss of commercial stocks and Asian countries became global producers and exporters of frog legs. After the ban of the frog trade in India in 1987, Indonesia arose as the main exporter of frog legs. In 2009, it accounted for 45% (4100 t) of the world exports (UN Comtrade, 2012; Warkentin et al., 2009). The Indonesian local market alone is 2 to 7 times this volume (Kusrini et al., 2006). The global frog market remains somewhat opaque: statistics are scarce and unreliable, and frogs harvested in the wild are not always properly identified and accounted for. It is still difficult to estimate the respective contributions of farmed and wild catch production (Warkentin et al., 2009; Gratwicke et al., 2010).

Environmental impact 

Biodiversity

The world demand for frogs has severely depleted some wild populations of amphibians, including the edible frog Pelophylax kl. esculentus in Europe and the Chinese edible frog Hoplobatrachus rugulosus (Gratwicke et al., 2010). Frog farming is notoriously difficult: Indonesia, who has developed frog farms in the past, has reverted since the mid-2000s to wild harvesting (Kusrini et al., 2006). Due to the lack of reliable data, it is difficult to say whether large scale frog harvesting is sustainable, but it is certainly a matter of concern. Hoplobatrachus tigerinus, a farmed species, is already in the CITES listings and other species are under consideration (Gratwicke et al., 2010; Warkentin et al., 2009). On the other hand, the American bullfrog (Lithobates catesbeianus), which has been promoted as a farmed species in Asia, is now considered to be a major pest outside its native range (GISD, 2012).

Waste management

While information is lacking, it is clear that the waste management of frog processing is a problem. For instance, 1000 t of frogs are processed annually in Adana (Turkey) yielding about 500-700 t of fresh waste (Tokur et al., 2008). In that regard, using this waste for livestock feeding could be a welcome solution.

Nutritional aspects
Nutritional attributes 

Frog waste meal is a nutrient-rich by-product, with a composition similar to that of fish meal: protein 65-71% DM, fat 7-17% DM and ash 13-24% DM (Tokur et al., 2008). There is limited information on the composition of whole frog meal, which seems to be less rich in protein (48% DM) than the waste (Ojewola et al., 2005). The calcium and phosphorus content are disputed, as recent work (Tokur et al., 2008; Ojewola et al., 2005) reports much lower values (0.1-0.2% Ca, 0.3-2% P) than earlier studies (5.6% P and 6.6% Ca in Rao et al., 1963). Differences in composition may be explained by the different bone and skin proportions of the waste materials, the frog species, the feeding habitat and the catching season (Tokur et al., 2008).

Potential constraints 

The skin of certain frogs (Dendrobatidae) is poisonous due to the presence of alkaloids (Daly et al., 2002) but frog species used for human consumption are from the non-toxic Ranidae family. Neither edible frogs or their corresponding waste should contain toxic alkaloids.

Poultry 

Poultry trials indicate that frog waste meal is a valuable replacement for fish meal in broiler diets. Gains and feed conversion were higher when frog waste meal was compared to fish meal in chick growth trials (Nair et al., 1975). In 192 day-old broiler chicks, supplementation of frog waste meal up to 9% in the diet gave better growth than those without any frog waste meal supplementation, although frog waste meal had lower digestibility than fish meal (Aryiani et al., 1984). Performance was not affected when frog meal replaced fish meal in broiler diets (Islam et al., 1994). Up to 10% frog waste meal was fed to chicks (day old to 252 days of age) and feed intake, feed conversion, gain and mortality was not found to differ from the fish meal control (Ali et al., 1995).

Fish 

African catfish

Frog waste meal

Frog waste meal included at 28% in the diet of catfish fry (Clarias batrachus) gave poor growth when compared to fish meal, poultry by-product meal and linseed meal but economic returns were higher or identical to that obtained with other diets (Hasan et al., 1989).

Frog meal

No difference in performance was observed in a 180-day growth trial when frog meal was fed to catfish (Clarias gariepinus) and compared to fish meal (Fagbenro et al., 1993). Frog meal from the edible frog (Pelophylax kl. esculentus) could be fed at up to a level of 40% in the diet for 42 days to catfish fingerlings (Clarias anguillaris) with good performance (Achionye-Nzeh et al., 2003).

Crustaceans 

Frog waste was found to be an excellent supplementary protein source for feeding giant river prawn fry (Macrobrachium rosenbergii) (Ranu et al., 1993).

Nutritional tables
Tables of chemical composition and nutritional value 

Avg: average or predicted value; SD: standard deviation; Min: minimum value; Max: maximum value; Nb: number of values (samples) used

Main analysis Unit Avg SD Min Max Nb
Dry matter % as fed 84.6 1
Crude protein % DM 67.7 2.7 64.6 70.8 4
Ether extract % DM 10.8 5.4 7.1 17.0 3
Ash % DM 20.6 5.0 13.2 23.5 4
Gross energy MJ/kg DM 20.1 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 1.0 1
Phosphorus g/kg DM 19.0 1
Potassium g/kg DM 14.0 1
Zinc mg/kg DM 296 1
Copper mg/kg DM 17 1
 
Amino acids Unit Avg SD Min Max Nb
Alanine % protein 5.6 1
Arginine % protein 5.8 1
Aspartic acid % protein 6.5 1
Glutamic acid % protein 10.6 1
Glycine % protein 8.9 1
Histidine % protein 2.4 1
Isoleucine % protein 3.4 1
Leucine % protein 6.1 1
Lysine % protein 5.4 1
Methionine % protein 4.6 1
Phenylalanine % protein 3.8 1
Proline % protein 7.7 1
Serine % protein 4.9 1
Threonine % protein 3.5 1
Tyrosine % protein 2.4 1
Valine % protein 4.0 1
 
Poultry nutritive values Unit Avg SD Min Max Nb
AMEn cockerel MJ/kg DM 14.1 *

The asterisk * indicates that the average value was obtained by an equation.

References

Nair et al., 1975; Rao et al., 1963; Thirumalai et al., 1977; Tokur et al., 2008

Last updated on 24/10/2012 00:44:13

Main analysis Unit Avg SD Min Max Nb
Dry matter % as fed 90.4 1
Crude protein % DM 47.3 1
Crude fibre % DM 1.7 1
Ether extract % DM 9.1 1
Ash % DM 17.9 1
Gross energy MJ/kg DM 19.0 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 1.9 1
Phosphorus g/kg DM 2.8 1
Potassium g/kg DM 1.3 1
Sodium g/kg DM 1.6 1
Magnesium g/kg DM 0.1 1
Zinc mg/kg DM 12 1
Iron mg/kg DM 18 1
 
Poultry nutritive values Unit Avg SD Min Max Nb
AMEn cockerel MJ/kg DM 12.8 *

The asterisk * indicates that the average value was obtained by an equation.

References

Ojewola et al., 2005

Last updated on 24/10/2012 00:45:44

References
References 
Datasheet citation 

Tran G., 2015. Frog waste meal and frog meal. Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. http://www.feedipedia.org/node/666 Last updated on May 11, 2015, 14:34

English correction by Tim Smith (Animal Science consultant) and Hélène Thiollet (AFZ)
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